Experimental observations of multiple-gap states in a strongly tunnel-injected non-equilibrium superconductor are reported. A phenomenological model based on quasi-particle diffusion successfully accounts for the qualitative features of these observations.

The influence of the electron-phonon interaction on electron-electron scattering in simple metals has been described within the framework of Landau Fermi-liquid theory. The predicted electron-electron scattering contribution to the low-temperature resistivity of Al is enhanced by a factor of ∼20 by the electron-phonon interaction and is in excellent agreement with recent experiments.

A spherical-model calculation of the spin-density-wave fluctuations in copper nuclear spins is presented. The results are compared with an experiment where copper nuclear spins have been cooled to below 0.1 μK. The agreement, with no adjustable parameters, is found to be satisfactory for spin susceptibility, entropy, and internal energy. A considerable depression of the transition temperature from its mean-field value, in qualitative agreement with the experiments, is also found.

To measure O-Al separation at Al(100) surfaces disordered (low-energy electron-diffraction beams extinguished) by reaction with oxygen, the extended appearance-potential fine structure was analyzed above the threshold for electron-bombardment excitation of the O $1s$ core. Calculation shows that the outgoing electron has angular momentum $l=0\mathrm{}$, allowing simple Fourier inversion of the fine structure. The separation, 1.98±0.05 Å, suggests that oxygen lies under the top layer, a result undetectable in extended-x-ray-absorption fine-structure measurements on thicker films.

A careful analysis of the Ward identities involving the axial divergences ${\partial }^{\mu }{A}_{\mu }$, combined with a fit to the $2\gamma$ decays of the ${\pi }^0$, $\eta$, and ${\eta }^{\prime }$ via the quantum electrodynamic anomaly, allows a consistent description of the pseudoscalar nonet with zero (or small) quantum chromodynamic surface term. The gluonic matrix elements $〈0\left|F\tilde{F}\right|P〉$ of the $\eta$ and ${\eta }^{\prime }$ obtained from the Ward identities lead to a good quantitative understanding of the relative rates $\frac{(\psi \to {\eta }^{\prime }\gamma )}{(\psi \to \eta \gamma )}$, and a qualitative understanding of the nonsuppression of ${\psi }^{\prime }\to \psi \eta$.

The inclusive $\gamma$ and ${\pi }^0$ momentum spectra from $\psi \mathrm{}\left(3100\right)\mathrm{}$ decay have been measured in $e^{+}{e}^{-}$ annihilation at SPEAR. When the $\gamma$ spectrum is compared with that expected from ${\pi }^0$ decay, an excess of high-momentum $\gamma \text{'}\mathrm{s}$ is observed. This excess is compared with that predicted by quantum chromodynamics for the decay of the $\psi$ into a $\gamma$ and two gluons.

It is proposed that the effective magnetic moment of quarks in hadrons should have an anomalous moment contribution because of the magnetic coupling of the photon to three or more gluons. We estimate this nonperturbative effect phenomenologically and find strong evidence for it from the measured decay rates $V\to P+\gamma$ and the observed magnetic moments of baryons.

The author points out that experiments to measure parity nonconservation in metastable atoms, such as hydrogen in the $2S$ state, are not, in general, made more sensitive by operating near level crossings in a magnetic field. New possibilities related to this observation are mentioned.

A new method for separating ions with different charge-to-mass ratio is described. It is based on the ponderomotive effect near the ion-cyclotron resonance.

It is shown that the spin-isospin dependence of low-energy $\Sigma N\to \Lambda N$ conversion leads to substantial quenching of nuclear-matter estimates of the widths of some $\Sigma$-hypernuclear states produced in ($K^{-}$, $\pi$) reactions, to a level below 10 MeV. The estimated widths compare favorably with those of the $\Sigma$-hypernuclear peaks recently observed at CERN for ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$. Tentative quantum number assignments are suggested for these states.

A measurement of the projectilelike fragments is reported for the collision of ${}_{}{}^{86}{}_{}{}^{}\mathrm{Kr}$ on ${}_{}{}^{166}{}_{}{}^{}\mathrm{Er}$ at a bombarding energy of 12.1 MeV/u. The results seem understandable only if a dynamical splitting of the projectilelike fragments is assumed.

A cascade relationship between molecular-orbital (MO) and separated-atom x rays has been utilized to study selected MO transitions. Depending on the mechanism of vacancy production, the observed MO spectra are interpreted as reflecting $2p\sigma \to 1s\sigma$ transitions or a mixture of $2p\sigma \to 1s\sigma$ and $2p\pi \to 1s\sigma$ transitions. The coincidence selection also directly corroborates a previous assignment of MO transitions to the $2p\sigma$ state.

Data demonstrating that, contrary to earlier results, laser-excited sodium Rydberg atoms may pass from low-electric field strengths to ionizing electric field strengths along two quite distinct paths is presented. One path involves predominantly adiabatic passage while the other path involves predominantly diabatic passage. Data are presented along with a model that supports this conclusion.

A compact, toroidal configuration of magnetized plasma is produced by a combination of $Z$- and $\theta$-pinch discharges. A paramagnetic toroidal field is produced by currents circulating in the plasma on closed flux surfaces.

Fundamental electron-cyclotron resonance damping for 4-mm waves with ordinary polarization as well as blackbody emission is measured along the midplane of the plasma in the Princeton Large Torus. Optical depths obtained from the data are in good agreement with those predicted by hot-plasma theory. The use of ordinary-mode fundamental electron-cyclotron resonance heating in existing and future toroidal devices is supported by these results.

The Brillouin backscatter fraction was measured from laser-produced spherical plasmas with prepared scale lengths of from 5 to 50 μm. The scale lengths in the region of $0.1<~\frac{n}{n_c}<~1$ were measured using double-pulse holographic interferometry. The backscatter energy was found to vary from 5% to 25% of the incident energy over the range of scale lengths measured. The spectra of the backscatter light were obtained and show the red shifts characteristic of Brillouin scattering.

We present a new approach to the ultrasonic attenuation in liquid helium, based on the Pippard-Buckingham-Fairbanks relations. An appropriate frequency-dependent generalization yields a theory with no adjustable parameters, in good agreement with experiment.

Calculations of the energy and angle variation of large-angle, inelastic, electron scattering produced by vibrations in a $c(2\mathrm{}\times 2)$ overlayer of CO on Ni(100) are presented. The results show pronounced structure related to the bonding site and symmetry associated with the adsorbed CO molecule. Limitations of the elementary form of the dipole-scattering formula applicable to the regime of small-angle scattering are also discussed.

By use of light scattering techniques a careful investigation has been made of the time dependence of the concentration fluctuations near the critical point of a binary liquid mixture. The experiments reveal deviations from exponential decay of these fluctuations at temperatures within 20 mdeg from the critical temperature. The observed deviations from exponential decay are in agreement with a recent theoretical prediction of Bhattacharjee and Ferrell.

Capillary shear flow of a magnetically aligned liquid crystal was studied in the three Miesowicz orientations in the nematic, the smectic-$A$ and, for the first time, in the reentrant nematic phase. These results indicate that the flow behavior of the reentrant nematic phase is essentially identical to that of the nematic phase and can be described by the hydrodynamic theory of the nematic phase.